当我更改其 View
值时,我的详细信息 @Binding
不会更新。
struct ContentView: View {
class ViewModel: ObservableObject {
@Published var imageSize: ImageSize?
@Published var anotherValue: Int? = 5
var cancellable: AnyCancellable?
init() {
cancellable = $imageSize.sink(receiveValue: { imageSize in
print("? \(imageSize?.rawValue ?? "Unknown")")
})
}
}
@ObservedObject private var viewModel = ViewModel()
var body: some View {
NavigationView {
List {
if viewModel.anotherValue == nil {
Text("Another value is nil")
} else {
NavigationLink(destination: SelectImageSizeView(selectedImageSize: $viewModel.imageSize)
.navigationBarTitle("ImageSize", displayMode: .inline)) {
Text("ImageSize: \(viewModel.imageSize?.rawValue ?? "Not Set")")
}
}
}
}
}
}
struct SelectImageSizeView: View {
@Binding var selectedImageSize: ImageSize?
var body: some View {
List{
ForEach(ImageSize.allCases, id: \.self) { imageSize in
HStack {
Button {
withAnimation {
self.selectedImageSize = imageSize
}
} label: {
HStack {
Text(imageSize.rawValue)
Image(systemName: imageSize == selectedImageSize ? "checkmark.circle.fill" : "circle")
}
.font(.title)
}
}
}
}
}
}
public enum ImageSize: String, Codable, CaseIterable {
case small = "Small"
case medium = "Medium"
case large = "Large"
}
当我将 NavigationLink
移出 if
块时它确实工作:
NavigationView {
List {
if viewModel.anotherValue == nil {
Text("Another value is nil")
}
NavigationLink(destination: SelectImageSizeView(selectedImageSize: $viewModel.imageSize)
.navigationBarTitle("ImageSize", displayMode: .inline)) {
Text("ImageSize: \(viewModel.imageSize?.rawValue ?? "Not Set")")
}
}
}
我在这里遗漏了什么吗?
答案 0 :(得分:1)
嗯。我不知道为什么会这样。但是您可以将整个 ViewModel
都忽略?
您必须将其放在 ContentView
之外。如果您不想从其他文件访问它,我已将其设为 fileprivate
。
对我有用。
fileprivate class ViewModel: ObservableObject {
@Published var imageSize: ImageSize?
@Published var anotherValue: Int? = 5
var cancellable: AnyCancellable?
init() {
cancellable = $imageSize.sink(receiveValue: { imageSize in
print("? \(imageSize?.rawValue ?? "Unknown")")
})
}
}
struct ContentView: View {
@StateObject private var viewModel = ViewModel()
var body: some View {
NavigationView {
List {
if viewModel.anotherValue == nil {
Text("Another value is nil")
} else {
NavigationLink(destination: SelectImageSizeView(viewModel: viewModel)
.navigationBarTitle("ImageSize", displayMode: .inline)) {
Text("ImageSize: \(viewModel.imageSize?.rawValue ?? "Not Set")")
}
}
}
}
}
}
struct SelectImageSizeView: View {
@ObservedObject fileprivate var viewModel: ViewModel
var body: some View {
List{
ForEach(ImageSize.allCases, id: \.self) { imageSize in
HStack {
Button {
withAnimation {
viewModel.imageSize = imageSize
}
} label: {
HStack {
Text(imageSize.rawValue)
Image(systemName: imageSize == viewModel.imageSize ? "checkmark.circle.fill" : "circle")
}
.font(.title)
}
}
}
}
}
}
public enum ImageSize: String, Codable, CaseIterable {
case small = "Small"
case medium = "Medium"
case large = "Large"
}
答案 1 :(得分:1)
这很愚蠢,但模拟器中存在错误。它正在与设备配合使用。